Copolymer, thermoplastic resin composition, and process for producing the same

ABSTRACT

A copolymer comprising a maleimide-based monomer unit and/or an unsaturated dicarboxylic acid anhydride-based monomer unit, where the copolymer contains an unreacted maleimide-based monomer and/or an unsaturated dicarboxylic acid anhydride-based monomer in an amount of 200 ppm or less and an adduct of a compound other than the polymerized units of the copolymer and the maleimide-based monomer and/or unsaturated dicarboxylic acid anhydride-based monomer in an amount of 0.1 to 3,000 ppm.

TECHNICAL FIELD

The present invention relates to a maleimide-based and/or an unsaturateddicarboxylic acid anhydride-based copolymer excellent in heatresistance, transparency, mechanical strength and moldability, unlikelyto thermal degradation, small in an extent of coloration anddeterioration occurring in the process of molding, and superior inappearance after molding, a thermoplastic resin composition comprisingsaid copolymer and a rubbery polymer, and processes for producing saidcopolymer and said thermoplastic resin composition.

BACKGROUND ART

Recently, in the fields of electric instruments and automobile industry,there has been a tendency of attaching importance to a design property,and materials used in these fields have been required to have a highmechanical performance, a light weight and an excellent appearance forsuch a tendency. In order to satisfy such a requirement,polycarbonate-based resins and polyphenylene ether-based resins, both ofwhich belong to a material field called engineering plastics, has beenused, and SMI resin, namely a copolymer of styrene andN-phenylmaleimide, has been developed and used. Although these resinsare superior in heat resistance, they are inferior in moldability.Currently, the shape of resin articles is becoming more complicated tosatisfy the desire for a design property and their wall thickness isbecoming smaller to satisfy the desire for lessening the weight. Undersuch a condition, an easiness of handling at the time of molding hasbeen paid an attention to as one of the material performances also froman aspect of improving the product yield and saving energy andresources. For such a viewpoint, a resin material superior inmoldability and having a heat resistance comparable to that ofengineering plastics has been required.

In order to improve a heat resistance of thermoplastic resins, a resincomposition prepared by blending a rubber-reinforced resin with an α-methylstyrene-based copolymer using α-methylstyrene as a component forthe copolymer is used. In this case, an inclusion of α-methylstyrene asa component of a resin matrix contributes to a heat resistance.Accordingly, this material has a fault that no sufficient heatresistance can be realized when the content of α-methylstyrene is low,while thermal degradation readily takes place in the process of moldingwhen the content of α-methylstyrene is high.

With the aim of overcoming the above-mentioned fault ofα-methylstyrene-based resins, a method of using heat resistant resinscomprising a maleimide-based copolymer or an unsaturated dicarboxylicacid anhydride-based copolymer has been proposed in JP-A 61-16955, etc.Further, JP-A-3-205411 has proposed a technique of producing such amaleimide-based copolymer or unsaturated dicarboxylic acidanhydride-based copolymer by the method of continuous solutioncopolymerization which is said to be desirable from the viewpoint ofmaking uniform a comonomer distribution in the copolymer.

However, the above-mentioned maleimide-based copolymer and unsaturateddicarboxylic acid anhydride-based copolymer contain unreactedunsaturated dicarboxylic acid anhydride-based monomer or unreactedmaleimide-based monomer etc., and these unreacted monomers are quitedifficult to remove.

In case the unreacted monomers such as unsaturated dicarboxylic acidanhydride-based monomer, maleimide-based monomer or the like remain inthe resin in a large quantity, there arises a problem that the resinbecomes colored at the time of molding. Further, there is a problem thatthe unreacted monomers vaporize and exhale to form a silver streak on asurface of molded article to deteriorate an appearance of moldedarticle. Further, there is a problem that the vaporized components ofthe unreacted monomers are deposited on a mold and contaminates themolded article as a soil to deteriorate an appearance of molded article.Although an operation of beforehand removing of volatile components suchas water are generally conducted by subjecting a resin to a preliminarydrying prior to molding, it is quite difficult to remove the unreactedmonomers by such an operation.

Accordingly, a lowness of the content of unreacted monomers in a resinis very important to the molding work.

It is an object of the present invention to obtain a maleimide-basedand/or unsaturated dicarboxylic acid anhydride-based copolymer which islow in the content of unreacted monomer such as a maleimide-basedmonomer, unsaturated dicarboxylic acid anhydride-based monomer and thelike, superior in heat resistance, transparency, mechanical strength andmoldability, unlikely to thermal degradation, small in an extent ofcoloration and deterioration occurring in the process of molding, andexcellent in appearance after molding; and a thermoplastic resincomposition comprising said copolymer.

DISCLOSURE OF THE INVENTION

The essentiality of the present invention consists in:

(1) a copolymer comprising a maleimide-based monomer unit and/or anunsaturated dicarboxylic acid anhydride-based monomer unit asconstitutional components, wherein said copolymer contains an unreactedmaleimide-based monomer and/or an unreacted unsaturated dicarboxylicacid anhydride-based monomer in an amount of 200 ppm or less and anadduct of a compound other than the constitutional components of saidcopolymer and said maleimide-based monomer and/or said unsaturateddicarboxylic acid anhydride-based monomer in an amount of 0.1 to 3,000ppm;

(2) a thermoplastic resin composition comprising, as constitutionalcomponents, (A) 20-90 parts by weight of a maleimide-based copolymercomprising (a) 15-65% by weight of a maleimide-based monomer unit and(b) 85-35% by weight of at least one monomer unit selected from thegroup consisting of an aromatic vinyl-based monomer and othervinyl-based monomer (the total amount of the monomer units (a) and (b)is 100% by weight), (B) 80-10 parts by weight of a graft polymerobtained by polymerizing at least one monomer selected from the groupconsisting of an aromatic vinyl-based monomer and other vinyl-basedmonomer in the presence of a rubbery polymer, and (C) 0-100 parts byweight of other thermoplastic resin, wherein said thermoploastic resincomposition contains unreacted maleimide-based monomer in an amount of10 ppm or less, a volatile component other than said maleimide-basedmonomer in an amount of 0.5% by weight or less as a total volatileamount, and an adduct of a compound other than the constitutionalcomponents of said maleimide-based copolymer and said maleimide-basedmonomer in an amount of 0.1 to 3,000 ppm;

(3) a process for producing a copolymer comprising, as constitutionalcomponents, a maleimide-based monomer unit and/or an unsaturateddicarboxylic acid anhydride-based monomer unit which comprises adding acompound other than the constitutional components of said copolymerbefore, during or after polymerizing a monomer mixture comprising themaleimide-based monomer and/or the unsaturated dicarboxylic acidanhydride-based monomer, or to a copolymer comprising said monomer unitsas constitutional components obtained by the polymerization; and

(4) a process for producing a thermoplastic resin composition whichcomprises polymerizing a monomer mixture comprising a maleimide-basedmonomer, an aromatic vinyl-based monomer and/or other vinyl-basedmonomer to form a maleimide-based copolymer comprising these monomerunits as constitutional components, and then adding to the resultingmaleimide-based copolymer a compound other than the constitutionalcomponents of said maleimide-based copolymer, said graft copolymer, andoptionally other thermoplastic resin.

BEST MODE FOR CARRYING OUT THE INVENTION

As the maleimide-based monomer which can be used for the production ofthe maleimide-based copolymer of the present invention, maleimide,N-methylmaleimide, N-ethylmaleimide, N-(n-propyl)-maleimide,N-isopropylmaleimide, N-t-butylmaleimide, N-cyclohexylmaleimide,N-phenylmaleimide, N-toluylmaleimide, N-xylylmaleimide,N-naphthylmaleimide and the like can be referred to.

Among these maleimide-based monomers, preferable areN-cyclohexylmaleimide and N-phenylmaleimide, and particularly preferableis N-phenylmaleimide. These maleimide-based monomers can be used aloneor in combination of two or more.

As the unsaturated dicarboxylic acid anhydride-based monomers which canbe used for producing the unsaturated dicarboxylic acid anhydride-basedcopolymer of the present invention, maleic anhydride, itaconicanhydride, citraconic anhydride and the like can be referred to, amongwhich maleic anhydride is preferable.

The content of the maleimide-based monomer unit in the maleimide-basedcopolymer of the present invention is preferably in the range of 15-65%by weight, and more preferably in the range of 20-50% by weight. Whenthe content of the maleimide-based monomer unit is less than 15% byweight, heat resistance of the composition which is an object of thepresent invention tends to become low. When the content of themaleimide-based monomer unit exceeds 65% by weight, there is a tendencythat a fluidity of the composition is inferior and no molded product canbe obtained at the time of molding or the resin formed is so brittlethat the molded article can be cracked at the time of demolding from themold.

In the unsaturated dicarboxylic acid anhydride-based copolymer of thepresent invention, the content of the unsaturated dicarboxylic acidanhydride-based monomer unit is preferably in the range of 5-50% byweight, and more preferably in the range of 10-40% by weight. When thecontent of the unsaturated dicarboxylic acid anhydride-based monomerunit is less than 5% by weight, the heat resistance which is an objectof the present invention tends to become low. When the content of theunsaturated dicarboxylic acid anhydride-based monomer unit exceeds 50%by weight, there is a tendency that a fluidity of the composition isinferior and no molded product can be obtained at the time of molding orthe resin formed is so brittle that the molded article can be cracked atthe time of demolding from the mold.

The aromatic vinyl-based monomer which can be used in the presentinvention include, for example, styrene, α-methylstyrene, vinyltoluenessuch as p-methylstyrene and the like, halogenated styrenes such asp-chlorostyrene and the like, p-t-butylstyrene, dimethylstyrene,vinylnaphthalenes and the like, among which preferable are styrene andα-methylstyrene. These aromatic vinyl-based monomers can be used aloneor in combination of two or more.

As said polymerizable other vinyl-based monomers which can be used inthe present invention, vinyl cyanide-based monomer, unsaturatedcarboxylic ester-based monomer and vinylcarboxylic acid-based monomeretc. can be referred to. As said vinyl cyanide-based monomer,acrylonitrile, methacrylonitrile, vinylidene cyanide and the like can beused, among which acrylonitrile is suitable for use as a startingmaterial of heat-resistant ABS resin. As said unsaturated carboxylicester-based monomer, for example, methyl acrylate, ethyl acrylate,propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, n-hexylacrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate,propyl methacrylate, butyl methacrylate, phenyl methacrylate, isobornylmethacrylate, benzyl methacrylate, trichloroethyl methacrylate,cyclohexyl methacrylate and the like can be referred to, among whichmethyl methacrylate is preferable. These unsaturated carboxylicester-based monomers can be used alone or in combination of two or more.As said vinylcarboxylic acid-based monomer, acrylic acid, methacrylicacid and the like can be referred to, among which methacrylic acid ispreferable. These other vinyl-based monomers can be used alone or incombination of two or more.

In the maleimide-based copolymer of the present invention, the totalcontent of the aromatic vinyl-based monomer unit and the copolymerizableother vinyl-based monomer unit is preferably in the range of 85-35% byweight, and more preferably in the range of 80-50% by weight. In theunsaturated dicarboxylic acid anhydride-based copolymer of the presentinvention, the total content of the above-mentioned monomer units ispreferably in the range of 95-50% by weight, and more preferably 90-60%by weight.

In the maleimide-based copolymer of the present invention, the contentof an unreacted maleimide-based monomer is preferably 200 ppm or less,more preferably 50 ppm or less and particularly preferably 30 ppm orless; and the content of total volatile components other than themaleimide-based monomer is preferably 0.5% by weight or less and morepreferably 0.3% by weight or less. The content of an adduct of acompound other than said constitutional components of the copolymer andsaid maleimide-based monomer is preferably 0.1-3,000 ppm, and morepreferably 0.1-1,000 ppm.

In the unsaturated dicarboxylic acid anhydride-based copolymer of thepresent invention, the content of an unreacted unsaturated dicarboxylicacid anhydride-based monomer is preferably 200 ppm or less and morepreferably 150 ppm or less; the content of total volatile componentsother than the unsaturated dicarboxylic acid anhydride-based monomer ispreferably 0.5% by weight or less; and the content of an adduct of acompound other than the constitutional components of the copolymer andsaid unsaturated dicarboxylic acid anhydride-based monomer is preferably0.1-3,000 ppm.

If the content of the unreacted maleimide-based monomer exceeds 50 ppmor if the content of the unreacted unsaturated dicarboxylic acidanhydride-based monomer exceeds 200 ppm, the copolymer tends to becomecolored and inferior in transparency, and at the time of fabricationthere can occur various troubles such as thermal coloration, bleed-out,flying of mists of maleimide-based monomer or unreacted unsaturateddicarboxylic acid anhydride-based monomer. As the total volatilecomponents other than maleimide-based monomer and/or unsaturateddicarboxylic acid anhydride-based monomer in the copolymer, the monomersof the constitutional components, organic solvents and residues ofoptionally used polymerization initiator and chain transfer agent can bereferred to. If total amount of these volatile components exceeds 0.5%by weight, heat resistance of the copolymer tends to be deteriorated anda silver streak can be formed at the time of molding. If the content ofthe adduct of maleimide-based monomer and/or unsaturated dicarboxylicacid anhydride-based monomer and compounds other than the constitutionalcomponents of said copolymer exceeds 3,000 ppm, heat resistance of thecomposition which is an object of the present invention tends to bedeteriorated.

In the thermoplastic resin composition of the present inventioncomprising a maleimide-based copolymer, a graft polymer and otherthermoplastic resin, the content of unreacted maleimide-based monomer ispreferably 10 ppm or less and more preferably 5 ppm or less; the contentof total volatile components other than maleimide-based monomer ispreferably 0.5% by weight or less and more preferably 0.3% by weight orless; and the content of the adduct of a compound other than theconstitutional components of maleimide-based copolymer and themaleimide-based monomer is preferably 0.1-3,000 ppm and more preferably0.1-1,000 ppm; both based on the thermoplastic resin composition.

The thermoplastic resin composition of the present invention comprises amaleimide-based copolymer, a graft polymer and other thermoplastic resinpreferably in amounts of 20-90 parts by weight, 80-10 parts by weightand 0-100 parts by weight, respectively, more preferably in amounts of30-80 parts by weight, 70-20 parts by weight and 0-70 parts by weight,respectively, and particularly preferably in amounts of 30-80 parts byweight, 70-20 parts by weight and 3-70 parts by weight, respectively.

If the content of the unreacted maleimide-based monomer in thethermoplastic resin composition of the present invention exceeds 10 ppm,the thermoplastic resin composition tends to become colored and therecan occur various troubles such as thermal coloration of the compositionat the time of molding, bleed-out, and flying of mists ofmaleimide-based monomer. The total volatile components other than themaleimide-based monomer in said thermoplastic resin composition includevolatile components originated from the maleimide-based copolymer,volatile components originated from the graft polymer and water etc. Iftotal amount of these total volatile components other than themaleimide-based monomer exceeds 0.5% by weight, heat resistance of thethermoplastic resin composition tends to be deteriorated and silverstreak can be formed at the time of molding. If the content of theadduct of the compounds other than the constitutional components of saidmaleimide-based copolymer and said maleimide-based monomer exceeds 3,000ppm, heat resistance of the composition which is an object of thepresent invention tends to be deteriorated.

The maleimide-based copolymer used in the thermoplastic resincomposition of the present invention can be the above-mentionedmaleimide-based copolymer of the present invention.

The graft polymer used in the thermoplastic resin composition of thepresent invention can be obtained by polymerizing at least one monomerselected from the group consisting of aromatic vinyl-based monomers andother vinyl-based monomer in the presence of a rubbery polymer andthereby graft-polymerizing said aromatic vinyl-based monomer and/or saidother vinyl-based monomer onto said rubbery polymer. As said aromaticvinyl-based monomer and said other vinyl-based monomer, the samearomatic vinyl-based monomers and copolymerizable other vinyl-basedmonomers as mentioned above as the constitutional components of themaleimide-based copolymer of the present invention can be referred to.The aromatic vinyl-based monomer and said other vinyl-based monomer usedherein may be identical with or different from said constitutionalcomponents of the maleimide-based copolymer of the present invention,and acrylonitrile, styrene, butyl acrylate and the like are preferablyused for this purpose.

As said rubbery polymer, the following can be used, though they are notlimitative: rubbery polymer latices obtained by mixing a latex of adiene-based polymer such as butadiene-styrene copolymer obtained bypolymerizing butadiene and/or styrene with an acid group-containingcopolymer obtained by polymerizing methacrylic acid and/or n-butylacrylate or the like; composite rubber latices of polybutadiene andbutyl acrylate rubber obtained by adding butyl acrylate, allylmethacrylate and/or 1,3-butyleneglycol dimethacrylate or the like to theabove-mentioned rubbery polymer latex and polymerizing the acrylatecomponents and the like; polyorganosiloxane latices obtained by mixingan organosiloxane such as octamethylcyclotetrasiloxane or the like withγ- methacryloyloxypropyl-dimethoxymethylsilane or the like; compositerubber latices of an organosiloxane and a butyl acrylate rubber obtainedby adding butyl acrylate, allyl methacrylate and/or 1,3-butyleneglycoldimethacrylate or the like to said organosiloxane latex and polymerizingthe acrylate component and the like; etc.

As said “other thermoplastic resin” which can be contained in thethermoplastic resin composition of the present invention, vinyl-basedpolymers obtained by polymerizing a vinyl-based monomer such asacrylonitrile and/or styrene and the like can be referred to, thoughthey are not limitative.

As a process for producing the maleimide-based and/or unsaturateddicarboxylic acid anhydride-based copolymer of the present invention,generally known polymerization processes can be adopted, and such aprocess can be carried out by adding a compound other than theconstitutional components of the maleimide-based and/or unsaturateddicarboxylic acid anhydride-based copolymer before, during, or after thepolymerization, or at any step of the production process such as drying,devolatilization, shaping, pelletizing, incorporation of other resins,stabilizers, etc. after the polymerization. It is preferable to add acompound other than constitutional components of the maleimide-basedand/or unsaturated dicarboxylic acid anhydride-based copolymer after acompletion of a solution polymerization in batch system or at the timeof eliminating the volatile components by means of a devolatilizingextruder, and it is particularly preferable to add said compound at thetime of eliminating the unreacted monomer, solvents, etc. by means of adevolatilizing extruder in a continuous solution polymerization system.

Similarly to the above, as a method for producing the thermoplasticresin composition of the present invention comprising a maleimide-basedcopolymer, a graft polymer and other thermoplastic resin, there can bereferred to a method of adding a compound other than the constitutionalcomponents of the maleimide-based copolymer at the time of producing themaleimide-based copolymer, a method of adding a compound other than theconstitutional components of maleimide-based copolymer before or duringa melt-kneading of maleimide-based copolymer, graft polymer and otherthermoplastic resin, etc.

The graft polymer contained in the thermoplastic resin composition ofthe present invention can be produced according to the generally knownpolymerization processes. In producing said graft polymer, 20-80 partsby weight of a rubbery polymer can be used as a solid component,together with 80-20 parts by weight of an aromatic vinyl-based monomerand/or other vinyl-based monomer.

The compound other than the constitutional components of themaleimide-based copolymer and/or the unsaturated dicarboxylic acidanhydride-based copolymer which is to be added to the composition ispreferably a conjugated diene-based compound or a compound forming aconjugated diene-based compound through a reaction. As said conjugateddiene-based compound, 1,3-butadiene, isoprene, chloroprene,cyclopentadiene, 1,3-cyclohexadiene, furan, anthracene and the like canbe referred to. As said compound forming a conjugated diene-basedcompound through a reaction, dicyclopentadiene and the like can bereferred to. Among the above-mentioned compounds, dicyclopentadiene isparticularly preferable. These compounds are incorporated into themaleimide-based and/or unsaturated dicarboxylic acid anhydride-basedcopolymer of the present invention in the form of an adduct with amaleimide-based monomer and/or an unsaturated dicarboxylic acidanhydride-based monomer preferably in an amount of 0.1-3,000 ppm andmore preferably in an amount of 0.1-1,000 ppm.

According to the need, a polymerization initiator, a chain transferagent, a heat stabilizer and the like can be added at the time ofproducing the copolymer of the present invention. As the polymerizationinitiators which can be used in the production of the copolymer of thepresent invention, generally known organic peroxides and azo compoundscan be referred to. Said organic peroxides include ketone peroxides,peroxy-ketals, hydroperoxides, dialkyl peroxides, diacyl peroxides,peroxy-esters, peroxy-dicarbonates and the like. As the chain transferagents which may be used according to the need at the time of producingthe copolymer of the present invention, mercaptans, terpene oils,α-methylstyrene dimer and the like can be referred to. As the additivessuch as heat stabilizer which can be used according to the need at thetime of producing the copolymer of the present invention, generallyknown ones can be used, although those obstructing the polymerization ormaking troubles such as coloration are undesirable.

In the production of the thermoplastic resin composition of the presentinvention, a dye, a pigment, a stabilizer, a reinforcing material, afiller, a flame retardant, a lubricant, an antistatic agent, adelustering agent and the like can be added according to the need.

Next, the present invention is explained more concretely by referring tothe examples. The invention is by no means limited by these examples.

In the examples presented below, the term “parts” means parts by weightand the term “%” means % by weight. Procedures of the measurements wereas mentioned below.

(1) Monomer composition ratio of a copolymer was determined byelementary analyses.

(2) The quantity of residual monomer in a copolymer was measured by gaschromatography. The total quantity of volatile components was calculatedas a sum of the quantity of residual monomer determined by gaschromatography and the quantity of water determined by Karl Fischermethod. The content of conjugated diene-based compound adduct wasmeasured by gas chromatography.

(3) Reduced viscosity of a copolymer was determined by dissolving 0.2gram of a sample copolymer in 100 ml of N,N-dimethylformamide andmeasuring the viscosity by means of Ubbelohde's viscometer at 25° C.

(4) Yellow index (YI) was determined by forming a sample copolymer intoa platy test piece having a thickness of 3 mm by means of a one ounceinjection molding machine at a cylinder temperature of 260° C. andmeasuring its YI according to ASTM D-1925. Vicat softening temperaturewas measured on a similar test piece according to ASTM D-1525 (4.9N).Izod impact strength was measured according to ASTM D256. Melt flow ratewas measured according to JIS K7210 at 220° C. under the condition of98N, provided that the quantity of flow per 10 minutes was measured andexpressed in term of grams.

(5) Pollution of a die (a mold) was evaluated by subjecting a copolymeror a thermoplastic resin composition to a molding by means of one ounceinjection molding machine at 350° C. repeatedly 100 times, and thenvisually examining the polluted state of die.

REFERENTIAL EXAMPLE 1 Synthesis of Diene-based Polymer

Into a pressure-resistant reactor equipped with a stirrer, 95 parts ofbutadiene, 5 parts of styrene, 0.2 part of t-dodecylmercaptan, 0.6 partof sodium oleate, 1.4 parts of potassium dehydroabietate, 0.3 part ofpotassium persulfate, 0.2 part of anhydrous sodium sulfate and 145 partsof deionized water were added and reacted at 70° C. for 10 hours withstirring to complete a polymerization reaction, thereby to obtain alatex of a diene-based polymer which is a butadiene-styrene copolymer.

REFERENTIAL EXAMPLE 2 Synthesis of Acid Group-containing Copolymer 1 asParticle-enlarging Agent

A reactor equipped with a stirrer was charged with 15 parts ofmethacrylic acid, 85 parts of n-butyl acrylate, 0.5 part of t-butylhydroperoxide, 0.003 part of ferrous sulfate, 0.009 part of disodiumethylenediaminetetraacetate, 1.8 parts of potassium oleate, 3.6 parts ofsodium dioctyl sulfosuccinate and 145 parts of deionized water, and apolymerization reaction was carried out at 63° C. for 4 hours to obtaina latex of an acid group-containing copolymer 1 as particle-enlargingagent.

REFERENTIAL EXAMPLE 3 Synthesis of Acid Group-containing Copolymer 2 asParticle-enlarging Agent

A reactor equipped with a stirrer was charged with 25 parts ofmethacrylic acid, 75 parts of n-butyl acrylate, 0.4 part of cumenehydroperoxide, 0.001 part of ferrous sulfate, 0.003 part of disodiumethylenediaminetetraacetate, 2 parts of potassium oleate, 1 part ofsodium dioctyl sulfosuccinate, 0.3 part of Rongalit C and 200 parts ofdeionized water, and a polymerization reaction was carried out at 70° C.for 4 hours to obtain a latex of an acid group-containing copolymerlatex 2 as particle-enlarging agent.

REFERENTIAL EXAMPLE 4 Preparation of Vinyl-polymerizable FunctionalGroup-containing Polyorganosiloxane

One hundred parts of a siloxane mixture was prepared by mixing 98 partsof octamethylcyclotetra-siloxane and 2 parts ofγ-methacryloyloxypropyl-dimethoxymethylsilane. After adding thereto asolution of 0.67 part of sodium dodecylbenzenesulfonate in 300 parts ofdistilled water and stirring the resulting mixture at 10,000 rpm for 2minutes by means of a homomixer, the mixture was once passed through ahomogenizer under a pressure of 30 MPa to obtain a stable preliminarilymixed latex of organosiloxanes.

Separately, 10 parts of dodecylbenzene-sulfonic acid and 90 parts ofdistilled water were poured into a reactor equipped with areagent-feeder, a cooler, a jacket heater and a stirring device toprepare a 10% aqueous solution of dodecylbenzenesulfonic acid.

While keeping the resulting aqueous solution at an elevated temperatureof 85° C., the preliminarily mixed organosiloxane latex was dropwiseadded thereto over a period of 4 hours, after which the resultingmixture was kept at the same temperature as above for one hour and thencooled. Then, the reaction mixture was neutralized with an aqueoussolution of sodium hydroxide.

The polyorganosiloxane in the latex had a weight-average particlediameter of 0.05 μm.

REFERENTIAL EXAMPLE 5 Preparation of Graft Copolymer (B-1)

To 60 parts (as expressed in terms of weight of solid component) of thediene-based polymer latex obtained in Referential Example 1 was added1.3 parts (as expressed in terms of weight of solid component) of theacid group-containing copolymer 1 latex as particle-enlarging agentobtained in Referential Example 2. After stirring the mixture for 30minutes at a low speed, 1% aqueous solution of sodium hydroxide wasadded in an amount of 0.09 part as expressed in terms of weight of solidcomponent, and the resulting mixture was kept stirred for an additional30 minutes at a low speed. As a result, there was obtained a latex ofrubbery polymer in which the particles were agglomerated to have a meanparticle diameter of 0.3 μm.

To 60 parts (as expressed in terms of weight of solid component) of therubbery polymer latex obtained above were added 0.45 part of dextrose,0.005 part of ferrous sulfate heptahydrate and 0.01 part of sodiumpyrophosphate, after which the mixture was heated to 65° C. Whiledropping thereto 13 parts of acrylonitrile, 27 parts of styrene, 0.3part of t-dodecylmercaptan and 0.2 part of cumene hydroperoxide over atime period of 140 minutes, a polymerization reaction was carried out.When the dropping was completed, 0.05 part of cumene hydroperoxide wasadded, and after 30 minutes, the same quantity as above of cumenehydroperoxide was additionally added. The resulting mixture was kept inthat state for 30 minutes, and then cooled.

The latex thus obtained was thrown into 0.4% aqueous solution ofsulfuric acid, in an amount twice of that of the latex, which hadpreviously been heated to 65° C., and then the resulting mixture washeated to 90° C. to coagulate the latex. After repeatedly washing thecoagulated latex with water and dehydrating it, the coagulated latex wasfinally dried to obtain an opaque white colored, powdery graft copolymer(B-1).

REFERENTIAL EXAMPLE 6 Preparation of Graft Copolymer (B-2)

To 45 parts (as expressed in terms of weight of solid component) of thediene-based polymer latex obtained in Referential Example 1 was added0.8 part (as expressed in terms of weight of solid component) of theacid group-containing copolymer 1 latex as particle-enlarging agentobtained in Referential Example 2, and the mixture was stirred for 30minutes at a low speed. Then, 1% aqueous solution of sodium hydroxidewas added thereto in an amount of 0.09 part (as expressed in terms ofweight of solid component) and the resulting mixture was further stirredfor 30 minutes at a low speed. Thus, there was obtained a rubberypolymer latex in which the particles were agglomerated to have a meanparticle diameter of 0.3 μm.

To 45 parts (as expressed in terms of weight of solid component) of therubbery polymer latex obtained above were added 0.35 part of dextrose,0.005 part of ferrous sulfate heptahydrate and 0.01 part of sodiumpyrophosphate, and the mixture was heated to 65° C. While adding thereto16 parts of acrylonitrile, 39 parts of styrene, 0.3 part oft-dodecylmercaptan and 0.3 part of cumene hydroperoxide over a timeperiod of 50 minutes, a polymerization reaction was carried out.Thereafter, the reaction mixture was kept in that state for 30 minutesand then cooled.

The latex thus obtained was thrown into 0.4% aqueous solution ofsulfuric acid, in an amount twice of that of the latex, which hadpreviously been heated to 65° C., and then coagulated by heating at 90°C. After repeatedly washing the coagulated product with water anddehydrating it, the coagulated mass was finally dried to obtain anopaque white-colored, powdery graft copolymer (B-2).

REFERENTIAL EXAMPLE 7 Preparation of Graft Copolymer (B-3)

While stirring 100 parts (as expressed in terms of weight of solidcomponent) of the diene-based polymer latex obtained in ReferentialExample 1, 2 parts (as expressed in terms of weight of solid component)of the latex of acid group-containing copolymer 2 as particle-enlargingagent obtained in Referential Example 3 was added thereto. The resultingmixture was further stirred for 30 minutes to obtain particle-enlargeddiene-based rubber latex. After a particle-enlarging operation, thepolymer had a mean particle diameter of 0.38 μm.

Subsequently, into a reactor equipped with a reagent-feeder, a cooler, ajacket heater and a stirring device was charged a mixture of 10 parts(as expressed in terms of weight of solid component) of the diene-basedrubber latex obtained above, 0.2 part of sodium N-lauroyl sarcosinateand 150 parts of deionized water together with 40 parts of butylacrylate, 0.3 part of allyl methacrylate, 0.1 part of 1,3-butyleneglycoldimethacrylate and 0.14 part of cumene hydroperoxide.

After blowing nitrogen gas stream through the reactor to replace theinner atmosphere with nitrogen, the inner temperature was elevated to60° C. When the temperature of the liquid in the reactor had reached 60°C., an aqueous solution prepared by dissolving 0.0001 part of ferroussulfate, 0.0003 part of disodium ethylenediamine-tetraacetate and 0.24part of Rongalit in 10 parts of distilled water was added to start aradical polymerization reaction. The reaction system was maintained inthat state for one hour to complete the polymerization of the acrylatecomponent. Thus, a latex of a composite rubber consisting of aparticle-enlarged polybutadiene and a butyl acrylate rubber wasobtained.

After the inner temperature of the reactor had descended to 60° C., anaqueous solution prepared by dissolving 0.4 part of Rongalit in 10 partsof distilled water was added, and then a liquid mixture of 6.3 parts ofacrylonitrile, 18.7 parts of styrene and 0.23 part of cumenehydroperoxide was dropped into the reactor over a period of 2 hours tomake progress a polymerization reaction. After the dropping, theresulting mixture was maintained in that state at 60° C. for one hour.Then, an aqueous solution prepared by dissolving 0.0002 part of ferroussulfate, 0.0006 part of disodium ethylenediaminetetraacetate and 0.23part of Rongalit in 10 parts of distilled water was added, andthereafter a liquid mixture of 6.3 parts of acrylonitrile, 18.7 parts ofstyrene and 0.23 part of cumene hydroperoxide was dropwise added over aperiod of 2 hours to make progress a polymerization reaction. After thedropping, temperature of the resulting mixture was kept at 60° C. forone hour, and then the mixture was cooled. Thus, a latex of a graftcopolymer in which acrylonitrile/styrene was graft-polymerized onto acomposite rubber consisting of particle-enlarged polybutadiene and abutyl acrylate rubber was obtained.

In the latex thus obtained, the mean particle diameter was 0.39 μm.

Subsequently, the polymer latex obtained above was thrown into a 0.15%aqueous solution of sulfuric acid, which had previously been heated to90° C., in amount three times of that of total latex with stirring tocoagulate the polymer. Then, the deposited mater was separated, washedand dried to obtain graft copolymer (B-3).

REFERENTIAL EXAMPLE 8 Preparation of Graft Copolymer (B-4)

A reactor equipped with a reagent-feeder, a cooler, a jacket heater anda stirring device was charged with 53.3 parts of the polyorganosiloxanelatex prepared in Referential Example 4 and 0.3 part of sodium N-lauroylsarcosinate, into which was then added and mixed 258.5 parts ofdistilled water. Subsequently, a mixture of 57 parts of butyl acrylate,0.3 part of allyl methacrylate, 0.1 part of 1,3-butyleneglycoldimethacrylate and 0.14 part of cumene hydroperoxide was added.

After replacing the inner atmosphere of the reactor with nitrogen gas bypassing a nitrogen gas stream, inner temperature of the flask waselevated to 60° C. When the inner temperature had reached 60° C., anaqueous solution prepared by dissolving 0.0001 part of ferrous sulfate,0.0003 part of disodium ethylene-diaminetetraacetate and 0.24 part ofRongalit in 10 parts of distilled water was added to start a radicalpolymerization reaction. Due to a polymerization of the acrylatecomponent, the liquid temperature ascended to 78° C. By maintaining thereaction mixture in this state for one hour and thereby completing thepolymerization of the acrylate component, there was obtained a latex ofa composite rubber made of polyorganosiloxane and a butyl acrylaterubber.

After the temperature of the liquid in the reactor had descended to 60°C., an aqueous solution prepared by dissolving 0.4 part of Rongalit in10 parts of distilled water was added, and then a liquid mixtureconsisting of 12.9 parts of acrylonitrile, 38.8 parts of styrene and0.23 part of cumene hydroperoxide was dropped over a period of 2 hoursto make progress a polymerization reaction. After the dropping, theresulting mixture was kept in that state at a temperature of 60° C. forone hour. Then, an aqueous solution prepared by dissolving 0.0002 partof ferrous sulfate, 0.0006 part of disodium ethylenediamine-tetraacetateand 0.23 part of Rongalit in 10 parts of distilled water was added, andthen a liquid mixture of 7.4 parts of acrylonitrile, 22.2 parts ofstyrene and 0.13 part of cumene hydroperoxide was dropwise added to makeprogress a polymerization reaction. After the dropping, the resultingmixture was kept in that state at a temperature of 60° C. for one hourand then cooled. Thus, there was obtained a latex of a graft copolymerin which acrylonitrile and styrene were graft-polymerized onto acomposite rubber consisting of polyorganosiloxane and a butyl acrylaterubber.

The graft copolymer in the latex had a weight average particle diameterof 0.13 μm. On the other hand, 150 parts of an aqueous solution preparedby dissolving aluminum sulfate in water so as to have a concentration of7.5% was kept stirred at a temperature of 60° C. One hundred parts ofthe latex of the graft copolymer obtained above was slowly and dropwiseadded to the stirred aluminum sulfate solution to coagulate the latex.The deposited matter was separated, washed and dried to obtain graftcopolymer (B-4).

REFERENTIAL EXAMPLE 9 Preparation of Vinyl-based Copolymer (C-1)

Using 25 parts of acrylonitrile, 75 parts of styrene, 0.2 part ofazobisisobutyronitrile and 0.5 part of t-dodecylmercaptan, a suspensionpolymerization (slurry polymerization) was carried out to obtainvinyl-based copolymer (C-1).

REFERENTIAL EXAMPLE 10 Preparation of Vinyl-based Copolymer (C-2)

Using 30 parts of acrylonitrile, 70 parts of styrene, 0.1 part ofazobisisobutyronitrile and 0.4 part of t-dodecylmercaptan, a suspensionpolymerization was carried out to obtain vinyl-based copolymer (C-2).

EXAMPLE 1 Maleimide-based Copolymer (A-1)

After replacing the inner atmosphere of a polymerization reactor havinga capacity of 20 liters and equipped with a stirrer with nitrogen gas,the following materials:

N-phenylmaleimide 25 parts Styrene 55 parts acrylonitrile 20 partsmethyl ethyl ketone 25 parts 1,1″-azobis (cyclohexane-1- 0.01 partcarbonitrile) t-dodecylmercaptan 0.05 part

were continuously fed into the reactor. While maintaining the reactor ata constant inner temperature of 110° C., the polymerization liquidmixture was continuously withdrawn by means of a gear pump placed at thebottom of the reactor so as to give an average residence time of 2hours. The polymerization liquid mixture which had been withdrawn wassubsequently made to stay in a heat exchanger kept at 150° C. for about20 minutes. Then, the mixture was introduced into a two-vent type doublescrew extruder having a cylinder temperature of 230° C. anddevolatilized, while keeping the first vent at an atmospheric pressureand the second vent at a reduced pressure of 2.67 kPa abs, and whilecontinuously feeding 0.38 part of dicyclopentadiene just before thesecond vent. The strand discharged from the extruder was pelletized bymeans of a pelletizer to obtain maleimide-based copolymer (A-1).Properties of the copolymer thus obtained were as shown in Table 1.

EXAMPLE 2

Using 0.12 part of dicyclopentadiene, a maleimide-based copolymer wasprepared in the same manner as in Example 1. Properties of the copolymerthus obtained were as shown in Table 1.

EXAMPLE 3

Using 0.07 part of dicyclopentadiene, a maleimide-based copolymer wasprepared in the same manner as in Example 1. Properties of the copolymerthus obtained were as shown in Table 1.

COMPARATIVE EXAMPLE 1 Maleimide-based Copolymer (A-2)

A maleimide-based copolymer (A-2) was prepared in the same manner as inExample 1, provided that the formed copolymer was extruded andpelletized by means of a vented double screw extruder without addingdicyclopentadiene. Properties of the copolymer thus obtained were asshown in Table 1.

EXAMPLE 4

Using 0.6 part of t-dodecylmercaptan, a maleimide-based copolymer wasprepared in the same manner as in Example 1, provided that the polymerwas extruded and pelletized while adding 0.39 part of dicyclopentadienejust before the second vent of double screw extruder. Properties of thecopolymer thus obtained were as shown in Table 1.

COMPARATIVE EXAMPLE 2

A maleimide-based copolymer was prepared in the same manner as inExample 4, provided that the polymer was extruded and pelletized bymeans of a vented double screw extruder without an addition ofdicyclopentadiene. Properties of the copolymer thus obtained were asshown in Table 1.

EXAMPLE 5

The maleimide-based copolymer obtained in Comparative Example 1 wasextruded and pelletized by means of a vented double screw extruder whileadding 0.05 part of dicyclopentadiene to 100 parts of themaleimide-based copolymer, at a cylinder temperature of 250° C. whilemaintaining the vent part under a condition of 2.67 kPa abs. Propertiesof the copolymer thus obtained were as shown in Table 1.

COMPARATIVE EXAMPLE 3

A maleimide-based copolymer was prepared in the same manner as inExample 5, provided that the polymer was extruded and pelletized bymeans of a vented double screw extruder without an addition ofdicyclopentadiene. Properties of the copolymer thus obtained were asshown in Table 1.

EXAMPLE 6

A mixture of 70 parts of the maleimide-based copolymer (A-1) obtained inExample 1 and 30 parts of the graft copolymer (B-1) obtained inReferential Example 5 was extruded and pelletized by means of a venteddouble screw extruder at a cylinder temperature of 250° C. and under acondition of 2.67 kPa abs of a vent part. Properties of thethermoplastic resin composition thus obtained were as shown in Table 2.

EXAMPLE 7

While adding 0.05 part of dicyclopentadiene to a mixture of 70 parts ofthe maleimide-based copolymer (A-2) obtained in Comparative Example 1and 30 parts of the graft copolymer (B-1) obtained in ReferentialExample 5, the resulting mixture was extruded and pelletized by means ofa vented double screw extruder at a cylinder temperature of 250° C. andwas maintained under a condition of 2.67 kPa abs of a vent part.Properties of the thermoplastic resin composition thus obtained were asshown in Table 2.

COMPARATIVE EXAMPLE 4

A pellet was prepared without an addition of dicyclopentadiene in thesame manner as in Example 7. Properties of the thermoplastic resincomposition thus obtained were as shown in Table 2.

EXAMPLE 8

While adding 0.1 part of dicyclopentadiene to a mixture of 70 parts ofthe maleimide-based copolymer (A-2) obtained in Comparative Example 1and 30 parts of the graft copolymer (B-3) obtained in ReferentialExample 7, the resulting mixture was extruded and pelletized by means ofa vented double screw extruder at a cylinder temperature of 250° C. andunder a condition of 2.67 kPa abs of a vent part. Properties of thethermoplastic resin composition thus obtained were as shown in Table 2.

COMPARATIVE EXAMPLE 5

A pellet was prepared without an addition of dicyclopentadiene in thesame manner as in Example 8. Properties of the thermoplastic resincomposition thus obtained were as shown in Table 2.

EXAMPLE 9

While adding 0.1 part of dicyclopentadiene to a mixture of 45 parts ofthe maleimide-based copolymer (A-2) obtained in Comparative Example 1,40 parts of the graft copolymer (B-4) obtained in Referential Example 8and 15 parts of the vinyl-based copolymer (C-1) obtained in ReferentialExample 9, the resulting mixture was extruded and pelletized by means ofa vented double screw extruder at a cylinder temperature of 250° C. andunder a condition of 2.67 kPa abs of a vent part. Properties of thethermoplastic resin composition thus obtained were as shown in Table 2.

COMPARATIVE EXAMPLE 6

A pellet was prepared without an addition of dicyclopentadiene in thesame manner as in Example 9. Properties of the thermoplastic resincomposition thus obtained were as shown in Table 2.

EXAMPLE 10

While adding 0.05 part of dicyclopentadiene and 0.2 part of magnesiumoxide to a mixture of 55 parts of the maleimide-based copolymer (A-2)obtained in Comparative Example 1, 40 parts of the graft copolymer (B-2)obtained in Referential Example 6 and 5 parts of the vinyl-basedcopolymer (C-2) obtained in Referential Example 10, the resultingmixture was extruded and pelletized by means of a vented double screwextruder at a cylinder temperature of 250° C. and under a condition of 3kPa abs of a vent part. Properties of the thermoplastic resincomposition thus obtained were as shown in Table 2. The extent of diepollution was found to be the smallest in this example in all examplespresented in this specification.

COMPARATIVE EXAMPLE 7

A pellet was prepared without an addition of dicyclopentadiene in thesame manner as in Example 10. Properties of the thermoplastic resincomposition thus obtained were as shown in Table 2.

EXAMPLE 11

Using 85 parts of methyl methacrylate, 9 parts of α-methylstyrene and 6parts of maleic anhydride, a bulk polymerization was carried out toobtain an unsaturated dicarboxylic acid anhydride-based copolymercontaining 0.12 part of unreacted maleic anhydride. Then, 0.4 part ofdicyclopentadiene was added to 100 parts of the copolymer obtained aboveand the resulting mixture was extruded and pelletized by means of avented double screw extruder at a cylinder temperature of 260° C. andunder a condition of 2.67 kPa abs of a vent part. Thus, an unsaturateddicarboxylic acid anhydride-based copolymer was obtained. Properties ofthe copolymer obtained herein were as shown in Table 3.

COMPARATIVE EXAMPLE 8

An unsaturated dicarboxylic acid anhydride-based copolymer was preparedby pelletizing the polymer without an addition of dicyclopentadiene inthe same manner as in Example 7. Properties of the copolymer thusobtained were as shown in Table 3.

It is apparent from the examples and comparative examples present abovethat, according to the present invention, there can be obtainedcopolymers and thermoplastic resin compositions having a much reducedcontent of unreacted maleimide-based monomer and/or unreactedunsaturated dicarboxylic acid anhydride-based monomer, and an appearanceof molded articles thereof is superior to that of molded articlesobtained from the copolymers according to prior art.

TABLE 1 Amount of residual Adduct of Composition of unreacted conjugatedVicat copolymer monomers diene-based Reduced softening Pollution PMI STAN PMI Others compound viscosity temperature of die (%) (%) (%) (ppm)(%) (ppm) (dl/g) YI (° C.) (Visuals) Example 1 25 55 20 20 0.28 770 0.6819 146 ∘ Example 2 25 55 20 20 0.29 750 0.68 19 146 ∘ Example 3 25 55 2010 0.29 750 0.68 19 146 ∘ Example 4 25 55 20 30 0.28 1,100 0.34 25 145 ΔExample 5 25 55 20 20 0.27 660 0.68 25 145 ∘ Compara. 25 55 20 580 0.270 0.68 22 146 x Example 1 Compara. 25 55 20 840 0.29 0 0.34 29 146 xxExample 2 Compara. 25 55 20 500 0.25 0 0.68 27 145 x Example 3 PMI:N-Phenylmaleimide ST: Styrene AN: Acrylonitrile Pollusion of die: ∘ Nopollution is visually noticeable. Δ Partial pollution is visuallynoticeable. x Pollution is noticeable visually. xx Remarkable pollutionis noticeable visually.

TABLE 2 Composition of resin Amount of Maleimide- Other residual Adductof based Graft thermo- unreacted conjugated Izod Vicat co- co- plasticmonomers diene-based impact softening Pollution polymer polymer resinPMI Others compound strength Melt flow Rockwell temperature of die(parts) (parts) (parts) (ppm) (%) (ppm) (J/m) (g/10 min.) hardness (°C.) (Visual) Example 6 (A-1) 70 (B-1) 30 10 0.21 350 100 1.7 110 130 ∘Example 7 (A-2) 70 (B-1) 30 5 0.23 80 110 1.5 110 131 ∘ Example 8 (A-2)70 (B-3) 30 10 0.27 110 80 2.3 114 132 ∘ Example 9 (A-2) 45 (B-4) 40(C-1) 15 5 0.29 190 100 3.7 102 119 ∘ Example 10 (A-2) 55 (B-2) 40 (C-2)5 5 0.26 80 120 3.2 105 122 ∘ Compara. (A-2) 70 (B-1) 30 50 0.22 0 1001.6 110 130 Δ Example 4 Compara. (A-2) 70 (B-3) 30 90 0.28 0 70 2.6 112130 x Example 5 Compara. (A-2) 45 (B-4) 40 (C-1) 15 140 0.27 0 100 3.8102 119 x Example 6 Compara. (A-2) 55 (B-2) 40 (C-2) 5 40 0.24 0 120 3.1105 123 Δ Example 7 PMI: N-Phenylmaleimide Pollusion of die: ∘ Nopollution is visually noticeable. Δ Partial pollution is visuallynoticeable. x Pollution is noticeable visually. xx Remarkable pollutionis noticeable visually.

TABLE 3 Amount of residual Adduct of Composition of unreacted conjugatedVicat copolymer monomers diene-based Reduced softening Pollution MAH MSMMA MAH Others compound viscosity temperature of die (%) (%) (%) (ppm)(%) (ppm) (dl/g) YI (° C.) (Visual) Example 11 6 9 85 140 0.25 1,8000.53 8 128 Δ Compara. 6 9 85 1,200 0.24 0 0.53 10 128 xx Example 8 MAH:Maleic anhydride MS: α-Methylstyrene MMA: Methyl methacrylate Pollusionof die: ∘ No pollution is visually noticeable. Δ Partial pollution isvisually noticeable. x Pollution is noticeable visually. xx Remarkablepollution is noticeable visually.

INDUSTRIAL APPLICABILITY

The maleimide-based copolymer, unsaturated dicarboxylic acidanhydride-based copolymer and thermoplastic resin composition containingthese copolymers according to the present invention are superior in heatresistance and exhibits an excellent moldability and appearance ofmolded article, and therefore can be used as molded articles in variousfields such as electronic and electric instruments, automobiles, etc.

What is claimed is:
 1. A composition comprising a copolymer comprisingpolymerized units of a maleimide monomer and/or polymerized units of anunsaturated dicarboxylic acid anhydride monomer, unpolymerized maleimidemonomer and/or unpolymerized unsaturated dicarboxylic acid anhydridemonomer in an amount of 200 ppm or less, and an adduct of a compound andsaid maleimide monomers and/or said unsaturated dicarboxylic acidanhydride monomers, in an amount of 0.1 to 3,000 ppm, wherein the adductis not an adduct of the copolymer.
 2. The composition according to claim1, comprising a copolymer comprising (a) 15 to 65% by weight ofpolymerized units of a maleimide monomer, and (b) 85 to 35% by weight ofpolymerized units of at least one monomer selected from the groupconsisting of an aromatic vinyl monomer and another vinyl monomer,wherein the total amount of (a) and (b) is 100% by weight, and whereinthe unpolymerized maleimide monomer is present in an amount of 50 ppm orless, and a volatile component other than the maleimide monomer ispresent in an amount of 0.5% by weight or less.
 3. The compositionaccording to claim 2, wherein the maleimide monomer isN-phenylmaleimide, the aromatic vinyl monomer is styrene, and the othervinyl monomer is acrylonitrile.
 4. The composition according to claim 1,wherein the composition comprises unpolymerized maleimide monomer in anamount of 30 ppm or less, a total volatile component other than themaleimide monomer in an amount of 0.3% by weight or less, and the adductin an amount of 0.1 to 1,000 ppm.
 5. The composition according to claim1, comprising a copolymer comprising: (a) 5 to 50% by weight ofpolymerized units of an unsaturated dicarboxylic acid anhydride monomerand (b) 95 to 50% by weight of polymerized units of at least one monomerselected from the group consisting of an aromatic vinyl monomer andanother vinyl monomer, wherein the total amount of (a) and (b) is 100%by weight, and wherein the composition further comprises unpolymerizedunsaturated dicarboxylic acid anhydride monomer in an amount of 150 ppmor less, a volatile component other than the unsaturated dicarboxylicacid anhydride monomer in an amount of 0.5% by weight or less, and theadduct in an amount of 0.1 to 3,000 ppm.
 6. The composition according toclaim 5, wherein the unsaturated dicarboxylic acid anhydride monomer ismaleic anhydride, the aromatic vinyl monomer is styrene orα-methylstyrene, and the other vinyl monomer is methyl methacrylate. 7.The composition according to claim 1, wherein the adduct is an adduct ofa conjugated diene.
 8. The composition according to claim 7, wherein theconjugated diene is 1,3-butadiene, isoprene, chloroprene,cyclopentadiene or 1,3-cyclohexadiene.
 9. A process for producing thecomposition according to claim 1, which comprises adding a compoundother than the copolymer to a monomer mixture comprising the maleimidemonomer, the unsaturated dicarboxylic acid anhydride monomer or amixture thereof, before, during or after polymerizing, or to a copolymercomprising polymerized units of the monomer.
 10. The process accordingto claim 9, wherein the compound comprises a conjugated diene or acompound forming a conjugated diene.
 11. A process for producing thecomposition according to claim 1, which comprises polymerizing a monomermixture comprising a maleimide monomer, an unsaturated dicarboxylic acidanhydride monomer or a mixture thereof, to form a copolymer comprisingpolymerized monomer units, introducing the copolymer into adevolatilizing extruder to remove the volatile components, and adding acompound other than the polymerized or unpolymerized monomer units tosaid devolatilizing extruder at the time of devolatilization.
 12. Theprocess according to claim 9, wherein the compound is dicyclopentadiene.13. A composition comprising: (A) 20 to 90 parts by weight of acopolymer comprising (a) 15 to 65% by weight of polymerized units of amaleimide monomer and (b) 85 to 35% by weight of polymerized units of atleast one monomer selected from the group consisting of an aromaticvinyl monomer and another vinyl monomer, wherein the total amount of (a)and (b) is 100% by weight, (B) 80 to 10 parts by weight of a graftpolymer obtained by polymerizing at least one monomer selected from thegroup consisting of the aromatic vinyl monomer and the other vinylmonomer in the presence of a rubbery polymer, and (C) 0 to 100 parts byweight of another thermoplastic resin, wherein said compositioncomprises unpolymerized maleimide monomer in an amount of 10 ppm orless, a volatile component other than said maleimide monomer in anamount of 0.5% by weight or less, and an adduct of a compound and saidmaleimide-based monomer in an amount of 0.1 to 3,000 ppm, where theadduct is not an adduct of the copolymer.
 14. The composition accordingto claim 13, wherein the maleimide monomer is N-phenylmaleimide, thearomatic vinyl monomer is styrene, and the other vinyl monomer isacrylonitrile.
 15. The composition according to claim 13, wherein theadduct is an adduct of a conjugated diene.
 16. The composition accordingto claim 15, wherein the conjugated diene is 1,3-butadiene, isoprene,chloroprene, cyclopentadiene, 1,3-cyclohexadiene, furan or anthracene.17. A process for producing the composition according to claim 13, whichcomprises polymerizing a monomer mixture comprising a maleimide monomerand an aromatic vinyl monomer and/or another vinyl monomer to form amaleimide copolymer comprising polymerized units of the monomers, andoptionally adding to the maleimide copolymer a compound other than thecopolymer, the graft polymer or other thermoplastic resin.
 18. A processfor producing the composition according to claim 13, which comprisespolymerizing a monomer mixture comprising a maleimide monomer and anaromatic vinyl monomer and/or other vinyl monomer to form a maleimidecopolymer, melt-kneading the maleimide copolymer with a graft polymerand, optionally, another thermoplastic resin by mixing, and adding acompound other than the polymerized and unpolymerized monomer units atthe time of melt-kneading.